1. Field of the Invention
The present invention relates to a heat insulator used for a residential floor and the like.
2. Description of the Related Art
Heat insulators made of various types of materials are used today. For example, as a heat insulator for residential heat insulation, a mineral-based heat insulator such as glass wool or rock wool, a plastic-based heat insulator such as rigid urethane foam or extruded polystyrene foam, or a heat insulator using a natural ingredient such as cellulose fibers or carbonized foam cork is put to use.
Patent Document 1 listed below discloses, as a residential heat insulator, a plate-like heat insulator that is fit between support members such as floor joists, pillars, and ceiling joists and composed of a foamed styrene resin molding or a rigid polyurethane foam.    [Patent Document 1] Japanese Patent Application Laid-Open No. H08-74345    [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-41041